AngularJS-MongoLab $resource update error - angularjs

Question

I am connecting AngularJS with MongoLab and trying to update the "users" collection.
AngularJS resource service:
angular.module("myApp.services", ["ngResource"])
.constant({
DB_URL: "https://api.mongolab.com/api/1/databases/mydb/collections/users/:id",
API_KEY: "[SOME_RANDOM_KEY]"
})
.factory("UsersService", ["$resource", "DB_URL", "API_KEY", function($resource, DB_URL, API_KEY) {
return $resource(DB_URL, { apiKey: API_KEY, id: "#_id.$oid" }, { update: { method: "PUT" }});
}]);
This is how I am trying to update my users collection:
angular.module("myApp", ["myApp.services"])
.controller("AppController", ["$scope", "UsersService", function($scope, UsersService) {
$scope.users = [];
$scope.getAllUsers = function() {
$scope.users = UsersService.query();
};
$scope.updateUser = function(user) { // user: firstName, lastName, email
//delete user._id;
UsersService.update({}, user, function() {
$scope.users = UsersService.query();
console.log("Users updated successfully");
}, function() {
console.log("Some problems updating the user", arguments);
});
};
}]);
When I try to update the user information, it throws an exception stating:
{ "message" : "cannot change _id of a document old:{ _id: ObjectId('[SOME_RANDOM_KEY]'), firstName: \"Anup\", lastName: \"Vasudeva\", email: \"anup.vasudeva#emal.com\" } new:{ _id: {}, firstName: \"Anup\", lastName: \"Vasudeva\", email: \"anup.vasudeva#email.com\" }"
I am new to MongoDB, so I don't understand why it is creating an empty _id object for the new user instance?

Answer 1

Try changing your $scope.updateUser function to the following:
$scope.updateUser = function (user) {
var userId = user._id.$oid;
user._id = undefined;
UsersService.update({id: userId}, user, function () {
$scope.users = UsersService.query();
console.log("Users updated successfully");
}, function () {
console.log("Some problems updating the user", arguments);
});
};
The update/replacement object ('user'), should not contain the _id property when being passed to UsersService.update(). Mongo will not replace the _id value, so the id will stay the same after the update.
One other thing that's changed in this function is that we're passing the user id as the first parameter of the UsersService.update() function so that mongo knows which document to update.